The present invention relates to a gas insulated switchgear, and in particular, to a compact gas insulated switchgear which can minimize a line-side unit and is suitable for installation thereof.
A gas insulated switch-gear apparatus is comprised of a breaker, disconnector, earthed-switch-gear, instrumental current transformer and the like as well as conductors for electrically connecting therebetween which are accommodated in a plurality of hermetically sealed containers which are filled with insulation gas. Because of its advantages and excellent properties suitable for provision of a compact size, insulation property and safety handling, it is installed widely in various electrical stations such as substations and the like.
A prior art of such a gas insulated switch-gear is disclosed, for example, in JPA Laid-Open No. 10-75513, 1997. Japan Electrical Society National Convention No.1592, which is comprised of accommodating a connecting conductor, a disconnector connected to the connecting conductor, a cable head connected to the disconnector, an arrestor one end of which is connected between the disconnector and the cable head, and a single phase voltage transformer one terminal of which is connected between a disconnector which is provided for one of the three phases and the cable head.
Further, other related arts are also disclosed in JPA Laid-Open Nos. 60-197106, 60-187217 and 60-183908, which comprise arrestors and cable heads which are arranged in close proximity therebetween in an isosceles triangle in the lower direction of the line-side unit thereof.
Conventional gas insulated switch-gears referred to above have attempted, in order to provide for a compact-sized apparatus, to reduce the size of apparatus and/or simplify the structure thereof by accommodating a plurality of devices in one unit on the line side among plural hermetically sealed container units. However, there is such a problem that because its arrestor which is one of components and is connected to an earthing line is disposed in the upper direction of the sealed container on the line side, a length of the earthing line becomes substantially long, thereby causing an operating potential of the arrestor to become higher. Further, in order to monitor a frequency of operation of the arrestor or the like, a weather protective box for housing a monitoring device must be provided external of the sealed container.
Still further, in the related art disclosed in JPA Laid-Open Nos. 60-197106, 60-187217, 60-183908, three-phase arrestors and cable heads are disposed in proximity to each other, therefore, there arise such problems that its construction becomes very complicated because of complicated connection necessitated for connecting of internal conductors and of external provision of a potential transformer, that because some cable head is also disposed toward the circuit breaker unit, it takes a substantial time in assembling a potential transformer, etc., and that minimization of the earthing line has not been taken into consideration.
A first object of the invention is to provide for a compact-sized gas insulated switchgear apparatus, which is accomplished by assembling a plurality of line side components and parts in one sealed container on the side of the line.
A second object of the invention is to provide for a compact-sized gas insulated switchgear apparatus wherein its earthing line connected to its arrestor can be minimized, and a monitoring device is installed under a sealed tank of the line side unit.
A gas-insulated switch-gear apparatus for accomplishing the aforementioned objects of the invention has a feature that the same is comprised of: a bus bar unit; a circuit breaker unit; and a line-side unit, wherein arrestors are disposed in the lower direction and toward the circuit-breaker unit within the line-side unit, and cable heads are disposed on the opposite side from the circuit breaker unit therein while in the upper direction therein, line-side dicsconnectors and a potential transformer are accommodated, and wherein these arrestors and cable heads are arranged approximately concentrically. Further, the same has such features that line side disconnectors, arrestors, potential transformer, and cable heads are accommodated advantageously within the line side unit, that three-phase circuit breakers accommodated within the circuit breaker unit are disposed linearly aligned, and that a surface section of exhaust cylinder of the circuit breaker in the direction of its linear alignment is formed flat in part.
Still further, the arrestors and the cable heads disposed in the lower part within the line side unit wherein also the line side disconnectors and the potential transformer are accommodated in the upper direction thereof are connected with circuit breakers within the circuit breaker unit via an insulation spacer using connection conductors, and wherein the line side disconnectors aligned linearly are disposed between the insulation spacer and the arrestors.
Still more, the connecting conductors for connecting the circuit breakers in the circuit breaker unit with the arrestors and the cable heads accommodated in the lower part of the line side unit which also accommodates the line side disconnectors and the potential transformer in the upper part thereof have a horizontal section in a part for connecting the arrestors and the cable heads and a vertical section in a part for connecting between the circuit breakers and the arrestors, and wherein the line side disconnectors are installed on the connecting conductors in the vertical section thereof.
Still further, in the upper direction of the cable heads, there are provided earthing devices which are aligned linearly, and further the potential transformer is disposed above these earthing devices. The arresters and cable heads are arranged along a periphery of the container in the line side unit. Two arrestors and two cable heads of a same phase are arranged in proximity. Earthing lines of the arresters and a monitor device are placed in the bottom direction below the line side unit.
Further, the line side unit of the gas insulated switch-gear apparatus of the invention, which accommodates three phase arrestors and three phase cable heads in the lower part therein, and the line side disconnectors as well as the potential transformer in the upper part therein, has such a feature that an arrestor and a cable head of the neutral phase are counter-positioned, that the other arrestors of the other phases are disposed on both sides of the neutral phase arrestor to form a first triangle between the counter-positioned neutral arrestor and the neutral cable head, and that the other cable heads of the other phases are disposed on both sides of the neutral phase cable head to form a second triangle therebetween, and wherein the second triangle is larger than the first triangle.
Still further, in the line side unit in the gas insulated switchgear apparatus of the invention, which accommodates the three phase arrestors and the three phase cable heads in the lower part therein and the line side disconnectors and the potential transformer in the upper part therein, the neutral phase arrestor and the neutral phase cable header are counter positioned opposite to each other in a virtual circle drawn within the line side unit. Then, another phase cable head, the neutral phase cable head, the other phase cable head, another phase arrestor, the neutral phase arrestor, and the other phase arrestor are arranged sequentially along the virtual circle.
Still more, in the triangle arrangements of the three phase cable heads and three phase arrestors described above, the triangle of the three phase cable heads is formed to be greater than that of the arrestors.